Classical and quantum conductivity in β-Ga₂O₃.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Semiconductor Physics

Background:

• Gallium Oxide (β-Ga2O3) is a promising semiconductor with a complex phonon structure due to its ten atoms per unit cell.
• Understanding charge transport in doped semiconductors like β-Ga2O3 is crucial for device applications.
• Doping disorder further complicates the phonon spectrum, impacting conductivity measurements.

Purpose of the Study:

• To investigate the conductivity, magnetoconductivity, and Hall coefficient of degenerate, homoepitaxial, (010) Si-doped β-Ga2O3.
• To explore a unified model for scattering theory that incorporates a temperature-dependent characteristic phonon temperature (Tpo).
• To determine if a single Tpo(T) function can accurately describe the temperature dependence of conductivity and magnetoconductivity across different semiconductor materials.

Main Methods:

• Measurements of conductivity (σ), quantum-based magnetoconductivity (Δσ), and Hall coefficient (RH) were performed on Si-doped β-Ga2O3 from 9-320 K and 0-10 kG.
• A novel temperature-dependent phonon model, Tpo(T) = 1.6 × 10^3{1 - exp[-(T + 1)/170]} K, was developed and applied.
• The model's effectiveness was compared with data from degenerate Scandium Nitride (ScN), a material with a simpler phonon structure.

Main Results:

• A simple, single function Tpo(T) effectively described the conductivity and magnetoconductivity of Si-doped β-Ga2O3 without additional fitting parameters.
• In contrast, ScN required a constant Tpo = 550 K for similar fitting accuracy, highlighting the impact of complex phonon structures.
• The study demonstrates that quantum conductivity measurements can provide insights into classical conductivity in disordered, multi-phonon systems.

Conclusions:

• A unified temperature-dependent phonon model successfully explains charge transport in complex semiconductors like β-Ga2O3.
• Quantum conductivity provides a powerful tool for understanding classical transport phenomena in disordered materials.
• The findings pave the way for improved modeling of electronic properties in advanced semiconductor materials.